Fight Night Round 4: The Physics of Fighting

It&#39;s clear that the developers behind EA Sports&#39; upcoming Fight Night Round 4 are aiming to exceed the already high mark set by 2006&#39;s Fight Night Round 3 in practically every capacity. As I wrote in my first look at the game last month, the developers at EA Canada behind FN4 have...

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It's clear that the developers behind EA Sports' upcoming Fight Night Round 4 are aiming to exceed the already high mark set by 2006's Fight Night Round 3 in practically every capacity. As I wrote in my first look at the game last month, the developers at EA Canada behind FN4 have been focusing a lot of time on making sure that real physics play a primary role in the ring action--resulting in what is clearly a faster and more impactful boxing experience. In fact, as gameplay producer Brian Hayes explains in this Q&A, the very presence of gameplay physics in FN4 is a departure for the series.

GameSpot: Let's start with Fight Night Round 3. In retrospect, what did you like about the physics system in that game, what has been carried over into FN4, and what did you think needed improvement?Brian Hayes: Physics only showed up during the knockdowns in Round 3. In the punch-by-punch gameplay, physics wasn't involved. Technologically, nothing has been carried over from Round 3. Fight Night Round 4 is completely new and built from the ground up. There are some basic concepts that remain the same--for example, punching the opponent in the head will hurt them--but other than that, it's a whole new game.

The biggest things that we wanted to improve on over Fight Night 3 were: capture the realism of the sport of boxing, capture the speed at which these athletes can throw punches, and the responsiveness of the controls. I think we have done a great job on delivering on all these fronts.

GS: Take us on a brief tour of the development of a physics engine in a game like Fight Night Round 4. Where do you start? With the bodies of the fighters themselves? The physics of the punch and block? Or some combination?

BH: Prototyping is a very important part of the development process. You don't build the entire thing at once and hope it all comes together at the end. The development team works on creating different components to prove that they can work. We worked on multiple components separately and simultaneously. Because prototyping doesn't require that the feature be developed to a level of quality meant for store shelves, it allows us to experiment with different systems. To answer the question, it's a combination. We had early prototypes to test the full-body collisions of two boxer models and prototypes to test the physics impact from punches in the game going at the same time.

Lennox Lewis throws a punch at... who? Is this the mysterious eighth and final heavyweight?

GS: Many EA Sports games deal with violent contact between bodies/players. Has there been any sharing of technology between other EA Sports titles when creating the engine in FN4?BH: When it comes to physics, Fight Night Round 4 is kind of leading the way here at EAC. We benefit from only having to worry about two boxers as opposed to 10 basketball players or 22 footballers (or soccer players, if you will). The teams share information all the time, but not every game can employ the same solutions because we are all faced with unique challenges based on the sport you're re-creating. With that said, other teams at EAC have started to look at how we are using physics and are researching if they can adopt some of our technology in their games.

GS: One thing we noticed looking at the game was the impact of every punch that makes solid contact. Even jabs look like they sting a lot more than in the previous game. What kind of physics calculations are made during a punch in FN4?

BH: Several. Speed, direction, friction, degree of contact, and angle of impact all play a factor. All of that information is determined when every punch lands and factored into the effect the punch has. The game runs at 60fps, but the physics calculations are actually running at 120fps to help get the most accurate data possible.

GS: One of the big complaints in FN3 was the lack of inside fighting. You've put some effort into that in this game--Tyson looks to be a beast inside. Can you describe the problems with inside fighting from a development standpoint and how you went about solving them?BH: The first step was going with the new physics-based gameplay engine. From the very start our designs were that it would allow for much closer interaction between the fighters and for us to really make the boxer's physical dimensions play a factor. One of the interesting things we noticed was that many of the gameplay balancing designs we had initially, for example making boxers with long reach less effective on the inside, started to appear before we began actually implementing them. Because of the way punches retarget based on boxer proximity and the way punch strength is being calculated, the taller, longer boxers were almost innately less effective at close range than the shorter fighters. That being said, the system didn't make itself, and the team was always iterating on the collision volumes and physics calculations to ensure the game played the way we wanted it to.

Mixing it up inside and underneath.

GS: Has the import of inside fighting opened up new techniques, such as Bernard Hopkins' method of clinching an opponent, turning him away from the ref, and working the body down low until the ref breaks up the clinch? In simpler terms: Can you punch in the clinch?

BH: In simple answer, yes and no. Clinching in our game is full-on clinching. You can press a button and attempt to tie your opponent up. We experimented with several hit-and-hold techniques and methods of contextual tie-ups, but they continuously dragged the user into hugfests when they didn't want to. That being said, due to the interaction between the boxers, you will see arms getting tangled or one boxer seemingly pushing down on the other guy's head while he's about to throw another punch, but all these interactions evolve organically from the other stuff the boxers are doing. It looks amazing and nobody has to spend 20 years in a Philly gym learning those dirty tricks of the trade. One of the techniques I like to use is to get body to body with the other boxer and then push off to create space, and as soon as I do that I fire off a punch right away to catch my opponent off guard.

GS: With FN4, the series moves away from the sometimes-awkward parry system in the previous game to a more straightforward blocking scheme. How does blocking work in FN4, and how does that affect the gameplay?

BH: Control-wise, blocking is much simpler. You can block high or low the same way you did in Round 3. There is no more left and right directional blocks and no more parries. However, blocking isn't perfect. We've incorporated the element of block strength that decreases when the opponent hits your block. So just covering up in front of a big bad heavyweight isn't going to do much good for very long. Eventually those punches will punch through your guard and do damage. This makes it more important to use head movement and footwork defensively.GS: How big a factor is boxer movement/momentum in the game, in terms of opening up angles for clear punching and for adding impact to a punch?

BH: Movement is a big factor. Footwork and head movement are really important defensive tools in the game, and because defense creates counterpunching opportunities, they are offensive tools as well. You will see refinements to the movement controls that really open up the number of things you can do in the ring. Momentum is factored in to the physics calculations for every punch. So if you are moving into the path of a punch, it will be more impactful, and if you move away from or roll with a punch, it will be less impactful.

A hard shot to Lewis' jaw.

GS: There seems to be much more variety in terms of how punches land--everything from solid shots to glancing blows. How are you calculating damage this time around? Also, how does fatigue/injury affect a fighter's punch/block accuracy?

BH: As mentioned above, there are several factors involved in calculating the force of each punch: the strength of the boxer and his current level of fatigue, the type of punch, the level of contact, the area of contact, and the level of fatigue of the opponent. And that is just high-level. There are people considerably more intelligent than me that are doing all the math. The effect of fatigue is something that we focused on in gameplay this year because many people had complaints about the stamina in Round 3. As your boxer becomes fatigued, their movement and punching gets less snappy, punches have less power, and they become more susceptible to incoming punches.